1. Field of the Invention
This invention relates to an electric metal foil-plated laminate sheet excelling in workability, heat resistance, water resistance, electrical properties and adhesion to metal foil.
2. Description of the Prior Art
It is widely known that thermosetting resins, particularly radical polymerization type thermosetting resins represented by unsaturated polyester resins are finding extensive utility in numerous applications because they exhibit high workability and curability during the course of molding and further because their cured products possess well balanced properties. Especially, fiber-reinforced resin composites (hereinafter referred to briefly as "FRP") obtained by combining such thermosetting resins with reinforcing materials represented by glass fibers are used in radar domes, tanks, ducts, dam, ships and bodies of vehicles, for example. They manifest outstanding properties in the various applications because the thermosetting resins and the reinforcing materials composite their respective properties.
Despite the outstanding properties owned by the FRP as described above, the properties of some if not all of FRP, depending on the field of the electric metal foil-plated laminate sheet, do not prove to be completely satisfactory.
To be more specific, an attempt at effectively deriving the outstanding properties of the resin such as heat resistance, water resistance and electrical properties tends to entail the disadvantage that said laminate sheet are liable to gain in rigidity and lost impact resistance and, while being processed by punching, suffer cracks and induce separation of layers of laminates. Conversely, an attempt at improving impact resistance and stability to endure the impact of punching results in the disadvantage that the aforementioned boards suffer from impaired resistance to heat and water and, on exposure to a highly humid atmosphere, absorbs water with an appreciable sacrifice of electrical properties, and tends to suffer blisters and cracks under the thermal impact from the soldering treatment.
Further, in the case of using copper foil or aluminum foil there is the disadvantage that an additional adhesive is specially added because of their poor adhesion to them.
An object of this invention, therefore, is to provide a novel electric metal foil-plated laminate sheet excelling in workability, heat resistance, water resistance, electrical properties and adhesion to metal foil.